The flipped classroom approach has grown in various disciplines; however, only few research studies are conducted in social sciences at K-12 settings. This action research investigated the impact of implementing a flipped classroom approach on students' motivation and learning the content knowledge in a suburban high school introductory psychology course. Also, students' perceptions about the effectiveness of a flipped classroom approach was explored. Data were collected from 58 high school students using teacher-made pre- and post-tests, student surveys, interviews and exit slips. Results indicated that student motivation, perceptions, and effectiveness of learning are supported in the flipped classroom due to increased opportunities for collaboration, review, and the incorporation of active learning. Implications for psychology teachers and other social science high school teachers were discussed, including extensive planning, allocation of class time for active learning activities, and preparation of students for becoming active learners.